Questions tagged [hvac]

(Heating, Ventilating, and Air Conditioning) For questions about installing, repairing, and troubleshooting HVAC systems.

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32 views

Wire placement for Honeywell evohome WiFi Controller power supply socket soldering

I'd like to solder the wires that have come loose from the socket of the power supply for my Honeywell evohome WiFi Controller but I don't know where the wires need to connect to the socket. Grateful ...
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27 views

Help me understand my wiring

I have a two zone system in my new house with 2 separate thermostats. I am trying to replace my thermostat on the first floor which I believe controls the second zone and is connected to the air ...
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21 views

HVAC contactor receives 27VAC on both control terminals, and does not close

We have a heat pump condenser unit in Florida here. It is a heat pump with "auxiliary/emergency heating". The heat pump mode is not working. We have made some good progress so far. When we ...
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1answer
63 views

HVAC -Can the fan run without the inducer's motor being on? [closed]

I have a HVAC system from around 2010. The digital thermostat has various fan settings - HIGH, MED, LOW, AUTO. The inducer motor seems to be OFF even though the fan is ON. I notice cool air running ...
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1answer
80 views

Artificially lowering CO2 concentration

Is there any way to realistically lower CO2 concentration in living rooms? Today only way to lower CO2 concentration is to basically bring the "fresh" air from the outside. But this is ...
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27 views

Will adding a transfer grill to the mechanical room help with water heater backdraft?

I have a small mechanical room in the basement with an HVAC system that has an open return at the base plenum under the furnace blower. There are no transfer grills and cold air returns to the ...
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3answers
2k views

Airflow too strong in one of the registers

I have a register in one of the rooms where the heat blasts at really high velocity and it gets incredibly hot in the winter (80+). My son has been complaining for years and I can’t seem to find the ...
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0answers
42 views

Replace Heat Exchanger on 15 year old furnace? [closed]

I've got two Carrier furnaces in my basement; 90% efficiency / 100k BTU and 60k BTU. Both are 15 years old. These Carrier furnaces are known to have fault secondary heat exchangers and Carrier (via a ...
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1answer
45 views

health effects from mold in HVAC [duplicate]

We noted a musty smell coming from our heating ducts in the last few heating seasons. We first tried the usual things like changing filters, cleaning dust, etc., but finally called an HVAC tech to ...
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1answer
64 views

Batts of fiberglass inside cavity return duct

My HVAC return ducts are run through the building cavities. In some places, this means a return duct is run through the joists in the basement ceiling (with a metal liner covering it). In more than ...
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0answers
14 views

Cracked heat exchanger or bad inducer motor causing pressure switch stuck open?

15 year old York GY9S furnace won't fire due to pressure switch stuck open. It has two pressure switches. One switch connects to the collector box & is set to close at -.40 inH20. I got -2.20+/- ...
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1answer
25 views

When adding an air return to the basement for the sake of habitable space, what considerations should I be making?

I am currently planning to create a finished office space in my basement. I understand that habitable spaces require service from both supply and return air. The house, ~2000sqft over 2 habitable ...
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20 views

Humidistat with Foggy Wet Windows

I just replaced my filter, open the damper, put it on low humidity, about -20 outside and still the windows are dripping wet. The line looks clear but I don't think I should mess with the little box/...
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1answer
35 views

Strange metallic/electrical smell coming from Samsung AHU

I have a 4YO house. After about 2 years a strong electrical/metallic smell started coming from our Samsung AM060JNZDCH/AA. We've had 3x different AC companies come to look at it, but no one has been ...
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30 views

How to get good HVAC quotes?

My natural gas furnace and air conditioner are 20 years old. I plan to gather quotes to replace them both. What do I need to do so that I get good quotes? I've heard HVAC contractors talk in an online ...
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1answer
45 views

Screwing in to an HVAC vent

I'm trying to mount a sliding barn door in a room. It has five holes in the rail for the lag screws to screw in to. One of the five holes is directly over an HVAC vent that leads to the upper floor - ...
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23 views

TH232 thermostat appears to reset every time I press any button

I have my underfloor heating set on a program timer, but wanted to change this for the winter. However, any time I press ANY button, the screen lights up as it should, but then goes blank and resets, ...
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2answers
67 views

How big of a duct and grill do I need for a central cold air return on a 3 ton system?

What size grill and duct do I need for my cold air return to fit between wall studs in the following scenario? I have an open-air return in my basement mechanical room with no cold air return ducts or ...
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1answer
39 views

Adding a c wire for a thermostat

Trying to add a C wire for a new Nest thermostat. Currently only have a Red and White wire. There are no other terminals available for the C wire on the furnace transformer. Red go to one end of the ...
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1answer
42 views

What Do I Lose With a Honeywell C-wire Adapter?

I'm upgrading to a smart thermostat, which requires a C wire. My current thermostat cable has 4 wires, no C wire. The controller in the furnace does have a C connection. The system has both heat and ...
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1answer
35 views

debugging thermostat wiring and nest power failure

UPDATE: the red and the white in the separate sheath do not connect to the thermostat, trying to find where they split. more info to come and thoughts on debugging ... I am trying to get a Nest to ...
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1answer
80 views

Is there such a thing as a digital millivolt thermostat that needs no batteries?

I only just discovered that there is such a thing as a millivolt thermostat in the first place (after unwittingly using one for the past 19 years :I ), so do go easy on me. It seems like it might be ...
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0answers
39 views

Smoke smell from condenser fan after tech shorts two connections

My 10+ years HVAC condensing unit's fan motor stopped working and I setup an appointment with a HVAC service repair company to take a look. The HVAC Condenser is a Goodman CPLJ42-1 and I watched the ...
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0answers
14 views

Honeywell HZ432 showing heat when cooling and cool when heating

First off...The system is heating when I call for heat and cooling when I call for cooling. so it seems to be functioning perfectly. The problem lies in the panel indicators. They show the exact ...
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0answers
49 views

Rheem 96V gas furnace with error code 61, then code 22. Blower error and high limit error

For the past few weeks I've had intermittent problems with my heat furnace. It looks like the blower motor was not always turning on and now it's flashing code 61. It would ignite and I can see on ...
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1answer
24 views

Compressor makes loud squealing noise as HVAC system shuts off

Is it a dangerous condition if the Compressor makes this squealing noise? I left my home for two weeks and when I came back my condenser fan motor wasn't working. So my compressor was running none ...
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1answer
44 views

Inducer motor turns off immediately after the pressure switch closes

My furnace is not working properly (ICM2805A control board, or Nordyne 624631A). When I turn it on, the inducer motor will start spinning and shut down immediately, the board will reset, and try again ...
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1answer
96 views

Proper size furnace filter?

I recently moved into a new house and found that the furnace didn't have a filter installed properly. Well, there was an old dirty one but it was just sitting upright against the right hand side of ...
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0answers
27 views

How to create a C-Wire from Honeywell R8888A/B

So Ive been trying to install a new Honeywell wi-fi thermostat. I have been unsuccessful in any event. I have a third wire unused at every thermostat in my home which is black. This black wire tuns ...
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2answers
62 views

Need I needed AC/Furnace replacement, or I can delay it for a year or two

I'm living in the Northeast of the US, so my ac/heat units are 12 years. My current setup is like this: Heat-pump on unit outside the house, and a furnace unit in the attic. The heat was not able to ...
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1answer
42 views

Test Thermostat with Multimeter without 'C' Wire

I'm hoping to replace my thermostat with an Arduino-powered one of my own. The furnace is a Trane XV90 Upflow 2-stage condensing gas-fired one with upgraded inducer motor using Trane Furnace Kit ...
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1answer
43 views

Re-installing plenum - flexduct work for relocated house

I relocated a small house to a new foundation but all the HVAC flexduct was destroyed by the move. I have the original Goodman 2.5 ton unit, circa 2003, and the 20'x20"x8" sheet metal ...
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0answers
41 views

Installing a vent grill when the floor is finished

Is it possible to install an HVAC vent grill in the finish floor? This is in the attic space under a sloped roof, where the floor doesn't run all the way to the roof, so we actually have access to the ...
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42 views

Have to switch furnace off twice to reset

My furnace inducer fan starts but the furnace does not fire, it is a Lennox Furnace installed in 2003. The LED lights indicate DS1 off DS2 Flashing. Changed the pressure switch out, checked inlet and ...
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1answer
34 views

How to balance in-floor heating with forced air heat pump

Background: we recently bought a two story house on a slab. It has in-floor heating run by an electric water boiler. It also has forced air run by a Trane heat pump. As we live in Canada its starting ...
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43 views

HVAC duct issues

Purchased a home a few months ago that was gut rehabbed with new AC + furnace + ductwork and left vacant for a year. A few weeks after moving in I took a chandelier out of the ceiling in the dining ...
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1answer
58 views

Connecting a Google Nest Power Connector to Lennox GSB8-E

Installing Nest thermostat, getting no c-wire error. Get the nest power connector, to attach to the circuit board of the boiler......and that is where I get lost. Green wire in center has 24V ...
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0answers
55 views

Did I blow a fuse? Wiring 7 wires to thermostat

Did I blow a fuse? I had taken pictures before I de-wired the unit. Turned off the circuit breaker (mixed up the terms its the switch boxes). The taken the whole unit off the wall, to fix the anchor ...
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1answer
71 views

What fixed my heating system?

My Emerson WiFi thermostat stopped connecting but otherwise seemed to be working fine so I followed troubleshooting steps and replaced the batteries with fresh ones. This failed to solve the problem, ...
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1answer
68 views

Why is my furnace turning on and lighting just fine then the gas turns off but the blower continues to run blowing cold air

My furnace comes on just fine. Runs for a little while and will raise the temp a degree or two then it shuts off but the blower still blows out cold air. Flame sensor had been replaced, air filter is ...
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0answers
28 views

Cant figure out wiring on HVAC and 2 wire oil furnace (to go with a Nest)

Trying to figure out this wiring, but not totally sure I have it right, HEAT does not come on. Nest thermostat with R,W,Y,G,O, unused Blue,Brown,Grey Oil furnace with R and W direct from thermostat ...
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1answer
42 views

Is the water pipe / plumbing insulation similar to air conditioner line insulation?

I'm trying to change a worn out insulation on the air conditioner outside of the house. Is the plumbing insulation similar to the insulation on the cold AC line (refrigerant line?) on the unit outside ...
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1answer
48 views

Is it normal for a connection piece at outdoor HVAC unit to sweat heavily?

I noticed the connection piece at my outdoor HVAC unit has been sweating heavily when in use. It is in the 70s recently so not particularly hot out. I am worried about corrosion. Is this normal or ...
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1answer
33 views

Two filters in furnace

My recently-bought house has a Rheem Criterion II gas furnace (model RGPH-15EARJR). Here is the manual: https://www.questargas.com/ForEmployees/qgcOperationsTraining/Furnaces/Ruud_GPH_GPJ_GLH_GLJ.pdf ...
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1answer
32 views

correct wiring solution

Purchased a Goodman GMT090-4B 90,000btu furnace used that was assured to operate perfectly, it looks brand new. There are 4 wires that come out the side of the housing that were used for power and ...
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1answer
128 views

How do I fix a loud intake vent?

In the master bedroom, there is one of four intake vents in the house, and this particular one is very loud. Our house has two vertical air shafts that run parallel to each other, one for supply and ...
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1answer
50 views

Installing a Nest Thermostat can't find circuit board

Hello so recently I have been wanting to install one of these nest thermostats into my home and realized I didn't have a C wire and it was recommended to install a google nest power connector, the ...
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2answers
40 views

C wire possibly on my boiler/heat pump

Hey so I know this is annoying and asked way too often but the wife wants a WiFi thermostat and of course I don’t have a “c” wire hooked up and there is no “c” terminal on my control board. We have ...
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1answer
23 views

Furnace has G (Fan) terminal but no wire can I connect it to my thermostat?

My goal is to add support for my furnace fan on my Nest Thermostat. Looking at the furnace the board has many terminals, but not all are connected. Can I connect the G terminal to the G terminal on my ...
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1answer
64 views

Adding a C Wire to a wall mounted gas heater for a WiFI Thermostat

I have a typical 2 wire thermostat for a wall mounted propane heater. I want to install a wifi honeywell thermostat. The thermostat is right next to the heater so running a third wire is no problem I ...

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